An agent’s cover is the role played by an agent to conceal that he is in reality a spy. Therefore, when you go “under cover,” you make believe that you are a different individual or you behave like you have another occupation other than being a spy.
To ensure that your “cover” is not exposed, (i.e. it is found out that you are a spy), the cover should assist you to describe the reason for your location and you engage in your role.